1. Field of the Invention
The present invention relates to a display device and a liquid crystal television, particularly to a display device and a liquid crystal television that comprise a power supply circuit that produces and outputs various power supply voltages from an inputted commercial AC power supply, and a control unit that outputs a control signal to a plurality of circuits, respectively, to control startup and shutdown of the circuits, the plurality of circuits comprising at least the power supply circuit and an optical source lighting circuit that is driven by the power supply voltage.
2. Description of Related Art
Circuitry of a display device is normally constituted by combining a plurality of circuits. When there is a failure in any of these circuits and the display device cannot be started, it is necessary to replace the entire circuit board or determine that circuit has a failure. For example, in case of a liquid crystal television, when the screen remains black and no image appears even if the power switch is turned on, possible causes lie in a tuner circuit, a video processing circuit, a backlight inverter circuit and various other circuits. Such a failure has been conventionally repaired by replacing each block circuit board or determining the faulty portion by checking voltages and waveforms one by one referring to circuit diagrams.
Japanese Unexamined Patent Publication Nos. H10-301535, 2003-216127 and 2004-126437 disclose techniques of providing a video display device with two types of power supplies: a battery power supply and an external power supply, in which when there is no input from the external power supply, the battery power supply is used as the power source.